SPE MS Well Collision Avoidance Management and Principles

Transcription

1 SPE MS Well Collision Avoidance Management and Principles S.J. Sawaryn, Consultant On behalf of the SPE Wellbore Positioning Technical Section (WPTS) Collision Avoidance Sub-Committee also referred to as ISCWSA

2 Slide 2 Introduction Well Collision Avoidance Not a new subject, but Current guidance Disparate Company specific Occasionally contradictory Goal: Standardise Rules Process Nomenclature Improve efficiency Reduce implementation errors Input to API RP78 development Nomenclature: Reference Well: The well being drilled Offset Wells: Adjacent wells

3 Slide 3 Well Collision Avoidance The adoption of a particular minimum allowable separation rule, no matter how conservative, does not ensure an acceptably low probability of collision Management & Practices Minimum Separation Rule

4 Slide 4 Offset Well Risk Classification HSE Risk Well Collision with it could result in an uncontrolled release of material: Hydrocarbons Chemical (e.g. H 2 S) Nuclear (e.g. radioactive material) Biological Physical (e.g. geothermal) or undermine facilities. (e.g. working mines, piles) Does not have to be at surface: Sub-surface blowouts Sub-sea releases Non-HSE Risk Well Can be addressed solely in financial terms Temporal risks - damage after the collision Remediation (access and time)

5 Slide 5 Well Collision Frequency Date No.* Collision Probability / /16330 Why the interest? *Offshore North Sea, GOM and Canada uncontrolled flow to surface Land based drilling activity increased Drilling pads Closer well spacing Conductor sharing Additional slots Poorly surveyed old well stock Unreported incidents? No uncontrolled flow? Changes in industry practices?

6 Slide 6 Well Collision Example Case Description Cause Avoiding Action 18* Offshore: Whilst drilling a fast ROP top hole section with a recognised collision risk, the well built angle faster than Human Factors anomalous expected. The first few MWD surveys Risk habituation? readings. failed QA\QC due to suspected magnetic interference. The rig crew rejected them entirely and continued to drill blind. They One-Column Format drilled into an offset well causing a kick, throwing the drillstring out of the hole. When investigated, plotting the rejected MWD surveys showed the well heading straight towards the offset Failure to plot, and manage Adhere to required practices, after each survey and project ahead. Collisions are still relatively rare But less so than indicated Major influence is well density Industry trends... added care * One of 19 HSE and Non-HSE incidents recorded over the last 15 years

7 Slide 7 Leading Indicators % of wells for which exemptions are required Helps detect weak signals Poedjono et. al. 2009

8 Slide 8 The Collision Avoidance Elements Quality Assurance Wellbore Survey Operations Management Effective Communication Collision Avoidance Management Minimum Allowable Separation Distance MASD Data Structure Integrity Principles Position Uncertainty Well Reference Point Wellbore Survey Program Element Separation Factor (SF) Dimensionless number Critical condition SF = 1 No. Cases Data structure integrity 4 Topic elaborated on in the 2 nd paper Position uncertainty - Well reference point 1 Wellbore survey program - Collision avoidance management 9 Wellbore survey operations 1 Quality assurance - Effective communication 3

9 Typical MASD Dispensations Slide 9 Effectiveness not predictable Energy still being put in Penetration always possible Penetration can be rapid Acceptable mitigations are those which reliably preserve the relative well separation and so reduce the probability of well to well contact Proposed Mitigation Multiple casing strings protecting the tubing Jetting instead of drilling Rotary drilling instead of motor drilling Drilling with a mill-tooth bit instead of a PDC bit Drilling with a dull or shirt tail bit Drilling with low ROP Monitoring the shakers for cement/steel Monitoring offset wellhead vibration Monitoring offset casing annular pressure Low angle of incidence between wells Soft formation

10 Slide 10 Graphical Representation of Well Separation Travelling Cylinder Simplest, documented method Key device to show tolerances Support plan review and approval Monitor progress / project ahead Assess closure between wells Shared situational awareness Training essential for its use Scan down the OFFSET well Orthogonal and end-to-end cases? Short radius drilling? North referenced, normal plane travelling cylinder diagram

11 Slide 11 Graphical Representation of Well Separation 3D Ladder Plot Well: Ref1-3D Ladder Plotl Well 6 Well 1 Well 2 Well 3 Well 4 Well 5 Shows each well s MASD Not direction specific Magnetic interference zone Well 7 Equivalent Magnetic Distance Line

12 Planning Phase Workflow Slide 12 Start Manage Allowable Deviation Re-plan Well Path Revise Survey Program Resurvey Offset Well Resurvey Relative Wellhead Position And / Or Re-evaluate Offset Well Classification Consider Ranging Other Compliant Options Yes Change Possible? J H No No Unable to Create Allowable Well Path Plan Engineered Well Path A Select & Classify All Appropriate Offsets B Wellbore Proximity Analysis SF Acceptable? K C D Yes End Construct E Tolerance Lines Consider F Operations Improvements Control Well Plan Revision and Prepare to Execute Plan End G Complete set of wellbores Offset Well Classification Use of SSSVs Operational improvements (F) can not alter the conditions or assumptions on which the scan is based

13 Slide 13 Execution Phase Workflow Start Confirm Preconditions Offset Status per Classification Approved Well Plan Revision Operational Conformance as per Plan Acquire and QC Directional Survey Measurement per Survey Program Calculate Position Project to Bit Project Ahead According to AC Plan B C A Preconditions met B, C, D, E, F, I Loop Stop Drilling Stop Drilling End Yes At TD? D No Wellbore Proximity Analysis E Yes No Accepta ble to Drill Ahead? Can Adjust? No F G Stop Drilling Refer to Planning Phase H Yes Drill Ahead to Next Survey Point I End Identify situations where the reference well is drilled significantly off-plan

14 Slide 14 Conclusions Well collisions remain an operational risk onshore and offshore Rigorous application of the Elements will help avoid collisions Collisions: Data, Collision Avoidance Management, Communication Risk habituation has played a significant part in a number of these Remediation costs for non-hse collisions generally higher than plan Analysis of collisions difficult (infrequent, reluctance to share data) Further work: barrier management / measure well to well separation

15 Slide 15 Acknowledgements / Questions The efforts and contributions to this paper made by the officers of the SPE Wellbore Positioning Technical Section (WPTS), the members of the Collision Avoidance Sub-Committee and the generosity of the member s respective companies for supporting their participation and attendance at meetings are gratefully acknowledged.